U.S. Pat. No. 5,563,422 discloses a series of manufacturing method regarding gallium nitride(GaN)-based III-V compound semiconductor devices and techniques of ohmic electrodes. FIG. 1 shows the dissection of said patented invention, which is about making a gallium nitride(GaN)-based III-V compound semiconductor light emitting diode 110 with P type electrode 115 and N type electrode 114. It contains: a substrate 111; a semiconductor stacking structure above that substrate with a N type gallium nitride(N-GaN)112-based III-V compound semiconductor and a P type gallium nitride(P-GaN)113-based III-V compound semiconductor; a N type electrode(first electrode) 114 making said N type semiconductor layer in contact; a P type electrode(second electrode) 115 making said N type semiconductor layer in contact; and a pad 116 above the second electrode 115.
The second electrode 115(P type electrode) contacts to P type semiconductor 113 by forming a metallic material layer such as gold/nickel (Au/Ni) and annealing the metallic material layers.
Among said gallium nitride (GaN)-based III-V compound semiconductor devices, the second electrode 115 includes Ti/Al or Au, the second electrode 115 contains one or more metallic alloy selected from the group of gold, nickel, aluminum, platinum, tin, indium, chromium and titanium, in which gold/nickel alloy has better effects.
Even the second electrode 115 is made of gold/nickel; its resistance between electrodes is 1 k.OMEGA., therefore, this invention offers a manufacturing method of the ohmic electrodes and the transparent conductive layer to lower serial resistance between the electrode and the gallium nitride.